New Drug May Help Diabetic Kidney Disease Patients

Patiromer appears to keep potassium levels in check, researchers say

SOURCES: George Bakris, M.D., professor, medicine, University of Chicago; Maria DeVita, M.D., nephrologist, Lenox Hill Hospital, New York City; July 14, 2015, Journal of the American Medical Association

TUESDAY, July 14, 2015 (HealthDay News) -- A new drug decreases dangerously high levels of potassium in people with diabetes-related kidney disease, a new study finds.

Potassium is necessary for the heart, kidneys and other organs to work normally, but damage to the kidneys can cause potassium levels to increase to dangerous levels. This condition is called hyperkalemia.

Elevated potassium levels are associated with sudden death -- your heart stops, said lead researcher Dr. George Bakris, a professor of medicine at the University of Chicago.

"High potassium is a problem seen in people with advanced kidney disease and advanced diabetes with kidney disease and with people with heart failure," Bakris explained.

The new drug, patiromer, significantly reduced potassium levels when taken for a month, researchers found. Moreover, that effect lasted for a year.

Patiromer is a powder you mix with water and drink twice a day.

Bakris said a change in diet has been the traditional approach to lowering potassium levels. Patients are told to avoid foods such as tomatoes, bananas and other fruits that are high in this mineral.

If diet fails to control potassium levels, patients are usually given the drug sodium polystyrene (Kayexalate), Bakris said. This drug, which has been around for over 40 years, works by binding potassium in the lower intestine. However, the binding power of Kayexalate is spotty, he said.

Patiromer works by reliably binding potassium throughout the entire gastrointestinal tract, which helps remove potassium from the body, he explained.

But whether patiromer changes outcomes for patients beyond lowering potassium levels isn't known, Bakris said. "We do not have any data like that yet. It's all speculative and theoretical," he said.

The current trial is the second of three required for approval by the U.S. Food and Drug Administration. Based on these findings, a phase 3 study was done in which patiromer appeared similarly effective, Bakris said.

The current study was funded by Relypsa, the maker of patiromer, and the results were published July 14 in the Journal of the American Medical Association.

For the study, Bakris and colleagues randomly assigned 306 patients with type 2 diabetes and high potassium to one of three doses of patiromer twice a day for a month.

Patients also took renin-angiotensin-aldosterone system inhibitors, such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs), before and during the trial.

Dr. Maria DeVita, a nephrologist at Lenox Hill Hospital in New York City, explained, "These medications help delay progression of kidney disease, [but] have the side effect of also causing increased potassium. This may result in the need to discontinue their use, taking away a weapon to fight progressive kidney deterioration."

The researchers found that all doses of patiromer significantly reduced potassium levels after a month and continued to keep levels low over a year. And for most patients, potassium levels remained low without falling below normal.

Over the course of a year, less than 6 percent of patients had potassium levels drop below normal; about 7 percent experienced abnormally low levels of magnesium, and 6 percent suffered from mild to moderate constipation.

"If you have advanced kidney disease, if you have been told by your physician that your potassium is high, if you have heart failure and you can't take certain medicine because your potassium is elevated, there is now a reliable agent that will reduce risk of your potassium going up and enable you to take these other medicines," Bakris said. "Theoretically, it should lead to better outcomes."

DeVita said this new drug could be a welcome tool.

"Dr. Bakris' study is a tremendous victory for the management of this serious abnormality," said DeVita, who was not involved with the study. "We look forward to more studies embracing its safety and success."

If patiromer is approved by the U.S. Food and Drug Administration, the author of an accompanying journal editorial urges the agency to consider requiring post-marketing studies. These should assess whether the drug slows kidney disease progression, reduces the need for dialysis and improves heart-failure outcomes, wrote Dr. Wolfgang Winkelmayer, chair of nephrology at Baylor College of Medicine in Houston.